Auto-redirect in presence of search parameters

index.js

@@ -1,24 +1,38 @@
 const storageType = 'localStorage'
 
-var data = {}
+let data = {}
 
 const infoEl = document.getElementById('info')
 const formEl = document.getElementById('search')
 
+const errors = {
+  missingQuery: new TypeError('Query is missing.'),
+  noFoundInstances: new TypeError('No instances were found.'),
+}
+
+function buildSearchURL (opts = {}) {
+  if (typeof opts.query !== 'string') throw errors.missingQuery
+  if (!('instances' in data)) throw errors.noFoundInstances
+  if (data.instances.length === 0) throw errors.noFoundInstances
+
+  // Random instance
+  const n = Math.floor(Math.random() * data.instances.length)
+  const instanceURL = data.instances[n]
+
+  // Build URL
+  const params = new URLSearchParams({
+    q: opts.query
+  })
+  const url = `${instanceURL}?${params.toString()}`
+  return url
+}
+
 // Register event listeners
 formEl.addEventListener('submit', (event) => {
   event.preventDefault()
-  if ('instances' in data && data.instances.length > 0) {
-    // Random instance
-    const n = Math.floor(Math.random() * data.instances.length)
-    const instanceURL = data.instances[n]
-    // Assign URL
-    const params = new URLSearchParams({
-      q: formEl.query.value
-    })
-    const url = `${instanceURL}?${params.toString()}`
-    location.assign(url)
-  }
+  location.assign(buildSearchURL({
+    query: formEl.query.value
+  }))
 })
 
 function locallyGetInstances () {
@@ -73,9 +87,19 @@ if (Date.now() > timestamp + 3_600_000 /* 1 hour */) {
   }
 }
 
+// Auto-redirect in presence of search parameters
+if (location.search.length > 0) {
+  const searchParams = new URLSearchParams(location.search.slice(1))
+  if (searchParams.has('q')) {
+    location.assign(buildSearchURL({
+      query: searchParams.get('q')
+    }))
+  }
+}
+
 if (data.instances.length > 0) {
   infoEl.textContent = `${data.instances.length} instances`
 } else {
   infoEl.classList.add('error')
   infoEl.textContent = '0 instances'
-}
+}